It has long been known to use heating, ventilation and air conditioning (HVAC) systems for enclosed structures. HVAC systems usually comprise one or more blowers connected to a circuit of ventilation ducts to control the amount and direction of airflow throughout the structure. While some fresh air may be introduced into the system, much of the air within the enclosed structure can be recycled through the system. HVAC systems are also typically employed, as the name suggests, to control the air temperature of the enclosed environment by controlling the temperature of the air directed therein.
Dark and damp conditions within the ducts of an HVAC system are conducive to the rapid growth and reproduction of contaminants such as molds, spores, bacteria, viruses and mildews which may be harmful to the people for whom the air traveling therethrough is intended. HVAC systems thus become a breeding ground for these contaminants. Inhabitants may suffer adverse physical reactions as a result, especially if they are allergic to any of the contaminants. This problem is exacerbated when the inhabitants themselves introduce additional contaminants into the HVAC system that may then multiply in the contaminant friendly HVAC environment and spread to other inhabitants located within the structure. Air filters have been introduced into HVAC systems in an attempt to remove contaminants passing therethrough before they reach inhabitants. However, these filters often become damp themselves and provide conditions which foster growth and reproduction of the contaminants.
It is known that certain UV light can control growth of or kill most contaminants currently known to exist within HVAC systems. Low-intensity UV radiation can be used to kill organisms growing on surfaces in HVAC systems, and high-intensity UV radiation can be used to kill airborne organism as they pass near a UV lamp. However, the effectiveness of UV lamps diminishes over time. As a result, the UV lamps must be replaced periodically to maintain the level of effectiveness they were designed for.